A semisynthetic, ergot alkaloid with antiparkinson and lactation inhibitory activities. Bromocriptine selectively binds to and activates the postsynaptic dopamine D2-like receptors in the corpus striatum of the central nervous system (CNS). D2-like receptors are coupled to inhibitory G-proteins, which inhibit adenylyl cyclase, thereby preventing signal transduction mediated via cAMP and leading to an inhibitory effect on neurotransmission. This improves Parkinson symptoms, such as dyskinesia. Bromocriptine also has an inhibitory effect on the anterior pituitary gland, which results in blockage of prolactin secretion, thereby suppressing lactation.